A pendulum is a string with a weighted object atached to the end of it.
Period (T) is the amount of time that a pendulum to complete one vibration in a pendulum.
longer pendulums = longer period and shorter pendulums = shorter pendulums = shorter periods
25.2 Wave Discrition
Simple Harmonic Motion is the back and forth motion of a pendulum.
If the pendulum is in simple harmonic motion then the movement is measured in a Sine Curve.
Sine Waves are waves that have two extreme points, the high point the crest and the low point the trough.
Image from : https:/.../ electronics/signals.htm Amplitude is the distence between the mid point of the wave to the crest or to the trough. Wavelength is the distence between one crest to the next crest and/or one trough to the next trough. Frequency in a vibrating object is the number of vibrations for a certain amount of time.
Frequency is measured in Hertz (Hz)
An exaple of Hertz is if there is one vibration per second its 1 Hz, and 50 vibrations a second its 50Hz.
Frequency and period are inverses of each other:
Frequency = 1/Period
Period = 1/Frequency
25.3 Wave Motion
Most information around us gets to us by some form of a wave.
Sound travels to our ears
Light travels to our eyes
Electromagnetic waves are picked up by signals that takes them to our radios.
Waves do not transport matter they only transfer energy.
Waves are carried by a disturance in a medium.
25.4 Wave Speed
The speed of the wave depends on the meduim its moving through.
Wave speed in air is about 330 m/s to 350 m/s (Depending on Temperature).
Wave speed in water is about 4x faster than through air.
A slinky is a good example of how to see a longitudinal wave, extend the slinky and push one end forward and watch waves move.
25.7 Interference
Interference Pattern is when 2 waves meet and either form a bigger or a smaller wave.
For example, if you drop 2 rocks in the water the 2 waves can overlap creating an interference pattern
When 2 waves come together and the trough and crest of the 2 waves match up then the wave is a Constructive Wave
When 2 waves come together and the trough of one wave meets the crest of the other wave and vice versa then the wave is a
Destructive Wave.
Image from:animals.howstuffworks.com
Interference patterns are easiest to see in the water.
image from:www.answers.com
in the picture the places where you see the stripes are the places where the waves are constructivly interfering or are In Phase
but where there is no waves right between the 2 waves is destructive interference or are Out of Phase
25.8 Standing Waves.
A Standing Wave is a wave that is formed when one end is fixed to a position and the other hand moves up and down, thus since the one end does not move
then the wave is reflected back.
image from: www.scienceforums.net Nodes are points in the standing wave that remain stationary depending on the speed of the wave. Antinodes are positions in the standing wave with the highes amplitude and is located halfway between the nodes.
25.9 The Doppler Effect.
The Doppler Effect is the change in frequency due to the motion of an object.
The Red Shift in the doppler effect is the decrease in frequency and occurs when an object moves away.
The Blue Shift in the doppler effect occurs when an object is moving twards you and is the increase in frequency.
If you are standing on the street and a screeming football fan in a car comes driving by with and airhorn blowing it out his window, you notice
that the sound gets louder really quick and when he is passed you the sound slowly decreases, this is beacsue of the doppler effect.
25.10 Bow Waves.
Bow Waves occur when an object in water moves faster than the water.
an exaple of this is swimming in the water, when you move forward you notice that there is a V-shaped wave given off when you move forward.
this is known as a Bow Wave because you are moving faster than the water you are moving in.
This happens not just in water but also when an aircraft breaks the sound barrier, when a jet goes faster than the speed of sound then there is a white cloud
that surrounds the nose, this is also a bow wave.
Image from : media-2.web.britannica.com
25.11 Shock Waves.
Shock waves come from a supersonic aircraft generates a three-dimentional wave.
Bow waves are 2 dimensional while a Shock wave is 3 dimensional.
When a Shockwave occurs there is a loud crackle that follows called a Sonic Boom.
Sonic booms cannot occur from a slower-than-sound, or subsonic aircraft because the tones are too slow to come off as one big sound but rather sounds more continuous.
Chapter 25 Vibrations and Waves
25.1 vibration of a pendulum
A pendulum is a string with a weighted object atached to the end of it.25.2 Wave Discrition
Simple Harmonic Motion is the back and forth motion of a pendulum.Image from : https:/.../ electronics/signals.htm
Amplitude is the distence between the mid point of the wave to the crest or to the trough.
Wavelength is the distence between one crest to the next crest and/or one trough to the next trough.
Frequency in a vibrating object is the number of vibrations for a certain amount of time.
- Frequency is measured in Hertz (Hz)
- An exaple of Hertz is if there is one vibration per second its 1 Hz, and 50 vibrations a second its 50Hz.
Frequency and period are inverses of each other:25.3 Wave Motion
Most information around us gets to us by some form of a wave.- Sound travels to our ears
- Light travels to our eyes
- Electromagnetic waves are picked up by signals that takes them to our radios.
Waves do not transport matter they only transfer energy.Waves are carried by a disturance in a medium.
25.4 Wave Speed
The speed of the wave depends on the meduim its moving through.- Wave speed in air is about 330 m/s to 350 m/s (Depending on Temperature).
- Wave speed in water is about 4x faster than through air.
Wave speed = frequency x wavelength (v=ƒλ)25.5 Transverse Waves
A Transverse Waves is is a wave that travels right angles.This Image from: library.thinkquest.org/ 15433/unit5/5-1.htm
25.6 Longitudinal Waves
A Longitudinal Wave is a wave where all the particals move along one direction (not at right angles).This image is from:library.thinkquest.org/ 15433/unit5/5-1.htm
A slinky is a good example of how to see a longitudinal wave, extend the slinky and push one end forward and watch waves move.
25.7 Interference
Interference Pattern is when 2 waves meet and either form a bigger or a smaller wave.For example, if you drop 2 rocks in the water the 2 waves can overlap creating an interference pattern
- When 2 waves come together and the trough and crest of the 2 waves match up then the wave is a Constructive Wave
- When 2 waves come together and the trough of one wave meets the crest of the other wave and vice versa then the wave is a
Destructive Wave.Image from:animals.howstuffworks.com
Interference patterns are easiest to see in the water.
image from:www.answers.com
in the picture the places where you see the stripes are the places where the waves are constructivly interfering or are In Phase
but where there is no waves right between the 2 waves is destructive interference or are Out of Phase
25.8 Standing Waves.
A Standing Wave is a wave that is formed when one end is fixed to a position and the other hand moves up and down, thus since the one end does not movethen the wave is reflected back.
image from: www.scienceforums.net
Nodes are points in the standing wave that remain stationary depending on the speed of the wave.
Antinodes are positions in the standing wave with the highes amplitude and is located halfway between the nodes.
25.9 The Doppler Effect.
The Doppler Effect is the change in frequency due to the motion of an object.- The Red Shift in the doppler effect is the decrease in frequency and occurs when an object moves away.
- The Blue Shift in the doppler effect occurs when an object is moving twards you and is the increase in frequency.
If you are standing on the street and a screeming football fan in a car comes driving by with and airhorn blowing it out his window, you noticethat the sound gets louder really quick and when he is passed you the sound slowly decreases, this is beacsue of the doppler effect.
25.10 Bow Waves.
Bow Waves occur when an object in water moves faster than the water.- an exaple of this is swimming in the water, when you move forward you notice that there is a V-shaped wave given off when you move forward.
this is known as a Bow Wave because you are moving faster than the water you are moving in.This happens not just in water but also when an aircraft breaks the sound barrier, when a jet goes faster than the speed of sound then there is a white cloud
that surrounds the nose, this is also a bow wave.
Image from : media-2.web.britannica.com
25.11 Shock Waves.
Shock waves come from a supersonic aircraft generates a three-dimentional wave.- image from www.chrisgood.com/ aircraft/
Sonic Booms and Shock waves occur when an aircraft "Breaks the sound Barrier" or moves faster than the speed of sound.